This disclosure relates generally to controls, and more specifically to controlling a tool for shaping a workpiece.
A wide variety of applications call for objects to be formed from general workpieces, where the object formation can include cutting the object from the workpiece. The precision required of the cut may depend on the particular application.
One application that can call for high precision is the shaping of bone during surgery. For example, in a surgery such as a total knee replacement (TKR), the bones to which a prosthetic knee may be attached, typically the femur and the tibia, can be shaped to facilitate stable and effective implantation of the prosthesis.
Some cutting systems achieve increased accuracy by fixating the workpiece, such as bone. Bone fixation can be accomplished using a screw(s) and/or a clamp(s) to secure the bone to a secure positioning brace. Fixation can be used for many robotic orthopedic surgery systems because such systems depend on a fixed target and cannot or do not track the target. Fixation may be used in robotic systems despite the risks to the patient that can include pain, infection, and increased recovery and rehabilitation periods caused by the invasive nature of fixation.
Robotic and other surgical systems may be susceptible to failure that can occur suddenly and can cause damage or injury to the subject. Controllable or detectible failure may be detected before harm is done. Undetectable failure may cause damage when the system appears to be functioning normally. If a robot provides power drive or power assistance to an operator, failure may result when the robot malfunctions because the operator may be unable to react in time or with sufficient force to prevent the robot components from injuring the subject. Robotic systems may also be undetectable failures, since the operator may not be in full or even partial physical control of the robot.
The disclosed methods and systems include a control method that includes providing a workpiece that includes a target shape, providing a cutting tool, providing a 3-D image associated with the workpiece, identifying the target shape within the workpiece image, providing a 3-D image associated with the cutting tool, registering the workpiece with the workpiece image, registering the cutting tool with the cutting tool image, tracking the workpiece and/or the cutting tool, transforming the tracking data based on image coordinates to determine a relationship between the workpiece and the cutting tool, and based on the relationship, providing a control to the cutting tool. The control can include an analog signal, a digital signal, a control to at least partially retract a cutting element associated with the cutting tool, a control to reduce the speed of a cutting element associated with the cutting tool, a control to stop a cutting element associated with a cutting tool, or another control.
The methods and systems can include representing the workpiece image using volume pixels (voxels), and classifying the workpiece image voxels based on the target shape. Accordingly, based on the relationship between the cutting tool and the workpiece, the methods and systems can include re-classifying the voxels based on the relationship.
The methods and systems can include providing an image based on CT scan data, X-ray data, MRI data, fluoroscopy data, and/or ultrasound data. The methods and systems can also include classifying such image data, represented as three dimensional volume pixels or xe2x80x9cvoxels,xe2x80x9d where classifying the image voxels based on the target shape includes distinguishing target shape voxels and workpiece voxels. In an embodiment, distinguishing target and workpiece voxels includes associating target shape voxels with the target shape and associating non-target shape voxels as waste. Color-coding voxels, such as target shape voxels associated with the target shape, can also be performed to distinguish voxels. The images and/or voxels can be displayed to a user to enable a user to view relative positions of the cutting tool and workpiece and/or target shape. In one embodiment, the methods and systems can include re-classifying the voxels based on the relationship.
Classifying and/or re-classifying voxels can include identifying mixture voxels that include part workpiece and part target shape, subdividing the mixture voxels, and iteratively identifying and subdividing mixture voxels to a predetermined voxel resolution. In one embodiment, mixture voxels can be understood to be voxels that can be associated with more than one classification, where exemplary voxel classifications can include target, workpiece, waste, empty, cutting tool, cutting element, or other classifications. Subdividing the mixture voxels can be performed based on an octree data structure. Further, the methods and systems can include recombining voxels having the same classification, where such recombining can generally be performed based on neighboring voxels of the same classification.
The methods and systems can also include a probe that can be calibrated and employed to register the workpiece and/or the cutting tool to the workpiece image and the cutting tool image, respectively. The disclosed tracker can include a tracking method and system based on providing one or more markers on or otherwise associated with the workpiece and/or the cutting tool. The tracker can measure and/or determine at least one position and at least one angle associated with the workpiece and/or the cutting tool, where in one embodiment, the tracker can track in three positions and three angles to provide six degrees of freedom. The tracked data can thus be transformed to an image coordinate system to allow an updating of the respective image positions, angles, etc.
The image updating can also include (re)classifying voxels associated with the workpiece, where the reclassification can be based on the tracking data associated with the workpiece and/or the cutting tool. Such classifying and/or reclassifying can include identifying voxels associated with the workpiece that are eliminated by the cutting tool. The classifying and/or reclassifying can also include identifying mixture voxels, subdividing the mixture voxels, and, iteratively identifying and subdividing mixture voxels until reaching a predetermined voxel resolution. As provided previously, identifying mixture voxels includes identifying voxels having more than one classification. The subdividing can be based on an octree data structure. Voxel recombination of voxels having the same classification can also be performed.
Accordingly, the methods and systems include providing a control based on determining a distance between the cutting tool image and the voxels classified based on the target shape. In one embodiment, the control can be based on increasing the size of the cutting tool image to determine whether the increased size cutting tool intersects with the target image. The cutting tool image can be increased by a fixed amount, and/or based on tracking data associated with the cutting tool. The control provided to the cutting tool can thus be based on the relationship between a cutting element associated with the cutting tool image, and voxels classified based on the target shape.
In an embodiment, the control provided to the cutting tool can be based on the relationship between the cutting tool image and the voxels classified and/or associated with the target shape, where the relationship can be based on collision detection and/or intersection detection between at least part of the cutting tool and voxels associated with the target shape.
In one embodiment, the workpiece image can be understood to be associated with voxels that can be further associated with a three-dimensional grid of voxels, where an image associated with the workpiece can be incorporated into the grid, and grid voxels can be identified as being associated with the workpiece. Some of the workpiece voxels can thus further be associated with the target shape.
The methods and systems include providing a control to the cutting tool by performing at least one of collision detection and intersection detection. Such control can performing at least one of collision detection and intersection detection between at least part of the cutting tool and the target shape of the workpiece image.
In the disclosed methods and systems, identifying the target shape includes classifying voxels associated with the workpiece image as at least one of workpiece and target shape. Accordingly, providing control to the cutting tool can include performing at least one of collision detection and intersection detection between at least part of the cutting tool and the target shape voxels. Providing control can also include providing a control based on a threshold distance between the workpiece image and the cutting tool image.
Also disclosed is a system that includes a cutting tool, a workpiece that includes a target shape, a tracker to provide tracking data associated with the cutting tool and the workpiece, and a controller to control the cutting tool based on the tracking data associated with the cutting tool and the tracking data associated with the workpiece. The cutting tool can include one or more cutting elements that can include one or more blade(s), one or more rotatable blade(s), one or more retractable blade(s), one or more water jet(s), one or more particulate jet(s), one or more lithotriptor(s) and/or one or more ultrasonic lithotriptor(s). The controller can control the cutting tool by providing a control to at least partially retract the cutting element(s), and/or at least partially reduce a rotation rate and/or change a cutting rate of the cutting element(s). The controller can transmit a control signal to the cutting tool, where the control signal includes an analog signal, a digital signal, and no signal.
The systems can include a tracker that includes or otherwise provides tracking data based on at least three positions and at least three angles. The tracker can include one or more first markers associated with the workpiece, and one or more second markers associated with the cutting tool. The markers or some of the markers can be one or more infrared sources, Radio Frequency (RF) sources, ultrasound sources, and/or transmitters. The tracker can thus be an infrared tracking system, an optical tracking system, an ultrasound tracking system, an inertial tracking system, a wired system, and/or a RF tracking system.
The systems also include one or more images associated with the workpiece and at least one image associated with the cutting tool. The workpiece image(s) can be registered to the workpiece, and the cutting tool image(s) can be registered to the cutting tool. Accordingly, the systems include a means to register the workpiece to the image(s) associated with the workpiece, and a means to register the cutting tool to the image(s) associated with the cutting tool. The registration means can include a probe that can be calibrated prior to registration. Registration can be performed by contacting locations on the workpiece and/or cutting tool with the calibrated probe.
The systems thus also include means to provide at least one image associated with the workpiece, and means to provide at least one image associated with the cutting tool. Such means can include Computer Aided Design (CAD), CT scan, MRI data, X-ray, fluoroscopy, and/or ultrasound, although other means can be used. The systems can update the images with tracking data using means to transform the tracking data between different coordinate systems. Such transformations can be mathematically effectuated.
The systems and methods can be applied to a workpiece that includes bone, cartilage, tendon, ligament, muscle, connective tissue, fat, neuron, hair, skin, a tumor, and an organ. The cutting tool can include an endoscopic instrument.
The controller can also include a collision detection module and/or an intersection detection module that can determine a relationship between the cutting tool and at least part of the workpiece.
Disclosed is a system that includes a workpiece having a target shape included therein, a tracker to track at least one of a cutting tool and the workpiece, and, a control system, the control system including instructions to cause a processor to track the cutting tool and the workpiece, to determine a relationship between the cutting tool and at least one of the workpiece and the target shape, and to provide a control to the cutting tool based on at least one of the relationship of the cutting tool and the workpiece, and the relationship of the cutting tool and the target shape. The control system can also include an image associated with the workpiece and an image associated with the cutting tool. The image associated with the workpiece can includes an image associated with the target shape, and/or at least part of the workpiece image can be designated and/or otherwise classified as being associated with the target shape.
The system also includes an image registration means, where the image registration means registers the workpiece to an image associated with the workpiece, and the image registration means registers the cutting tool to an image associated with the cutting tool, and wherein the control system includes instructions to update at least positions of the workpiece image and the cutting tool image based on data from the tracker; and, where at least one of the relationship of the cutting tool and the workpiece, and the relationship of the cutting tool and the target shape, are based on the updated image positions.
In the disclosed systems, the relationship between the cutting tool and the workpiece can be based on position data and/or angle data associated with the cutting tool(s) and/or the workpiece, where the position data and angle data can be based on the tracker. The relationship between the cutting tool and the target shape can thus be based on position data and/or angle data associated with the cutting tool and/or the target shape, where the position data and angle data are based on the tracker. The instructions to determine a relationship between the cutting tool and the target shape and/or workpiece can also include instructions to represent the workpiece as a group of volume pixels (voxels), classify voxels corresponding to the target shape, represent the cutting tool as a group of voxels, a surface model, and/or using constructive solid geometry or other geometric modeling, and, based on the tracker data, classify and/or update the voxels. The instructions to classify voxels corresponding to the target shape can include classifying voxels as target shape and classifying voxels as waste, and/or instructions to color-code voxels corresponding to the target shape. In an embodiment, the workpiece can be represented as a surface model
The disclosed methods and systems can include a control for a shaping tool that can be referred to herein as a cutting tool, and in one embodiment, is a freehand shape cutter, but can be understood to be a tool that can cut, shave, and/or grind. References herein to a shaping tool or cutting tool can accordingly be understood to represent a tool that can cut, shave, and/or grind.
The disclosed methods and systems include a freehand shape cutter that includes a handheld cutting tool having a cutting element and a first marker. A second marker can be affixable to a workpiece that includes a target shape. A tracker can track a position of the cutting tool based on a position of the first marker, and also track a position of the workpiece based on a position of the second marker. A controller can control the cutting element based on the position of the cutting tool and the position of the workpiece to prevent the cutting element from invading the target shape.
In one exemplary embodiment, the methods and systems include a method of shaping a bone by determining a target shape of the bone, aligning the target shape with the bone, providing a handheld cutting tool having a cutting element, tracking the bone and the cutting tool, cutting the bone with the cutting tool, and controlling the cutting element to prevent invasion of the cutting tool on the target shape. In such an embodiment, the target shape of the bone can be determined by creating a bone model based on geometrical data of the bone, and establishing the target shape based on the bone model.
In one embodiment, the cutting tool can have six degrees of freedom, and the tracker can track with six degrees of freedom.
The cutting element can include at least one of a blade, a rotatable blade, a retractable blade, a water jet, a particulate jet, a lithotriptor, and an ultrasonic lithotriptor. The controller can control the cutting element by at least one of stopping the cutting element, retracting the cutting element, progressively retracting the cutting element, switching off the cutting element, and interrupting power to the cutting element. The tracked and/or determined positions can be three-dimensional positions that can be tracked substantially simultaneously. Additionally and optionally, the positions can be tracked continuously.
The target shape may be represented in the controller as a virtual template. The workpiece can include, for example, at least one of bone, cartilage, tendon, ligament, muscle, connective tissue, fat, neuron, hair, skin, tumor, and an organ that can include skin, brain, meninges, palate, tongue, esophagus, stomach, duodenum, jejunum, ileum, colon, liver, kidney, spleen, pancreas, ganglion, heart, artery, vein, arteriole, venule, capillary, lung, trachea, bronchus, bronchiole, alveolus, blood, extremity, and a reproductive organ. A tumor can include a neoplasm, a benign tumor, a hyperplasia, a hypertropy, a dysplasia, an anaplasia, a metaplasia, a metastasis, and a malignant tumor.